Conversion of butanes into high antiknock motor fuel



Feb. 13, 1945. E. L. DouvlLLE ETAL. 2,369,444

CONVERSION OF BUTANES INTOH'IGH ANTIKNOCK MOTOR FUEL Filed Sept. 9, 1940 Patented Feb. 1 3, 1.9455` UNITED STATES PATENT o'FEic-E CNVRSION F BUTANESINTO HIGH ANIIKNOCK MOTOR` FUEL i Edmond L. d0uville and Bernard L. Eyering, Chicago, Ill., assignors'to Standard 0il.Company, l Chicago, Ill.,l a corporationoi.' Indiana application September 9, 1940, Serial No. 355,950 4 10mm. (ol. 26o-essai afn wax whereby an intermediate fraction boiling in the motor fuel range is formed consistingl 'almost entirely of branched-chain paraffin hydrocarbons.

`In the operation of most petroleumreflneries and particularly in natural gasoline and distillate recovery plants large quantities 'of the butanes areY available.v These hydrocarbons have a number of uses, including their use as fuel either alone or blended in limited` quantities in gasoline andthe like. Also, a number of methods are lavailableA for converting them into motor fuels, but .most of these require a number of produce motor fuels of the highest quality or require another valuable material such as one or more hydrocarbons of the olefin series. For

example, a fraction rich in butanes. can be polyv merized thermally butl the product is unsaturated and therefore not well suited for use as aviation gasoline, .By dehydrogenating the buta'n`es,oleA `fins are produced which can be polymerized either thermallyl or catalytically'lnto motonf'uels which are likewise` unsaturated. :of this type isobutane can be converted into isolocten'e which, upon hydrogenatiorl. yields viso octane. This is, of course, an excellent aviation fuel constituent but theprocess involved is relatively expensive becauseof the ynumber of opera- In a special process' larly adapted to such service due to their high antiknock lvalues, freedom from gum-forming tendencies andrelativelyhigh heat content ,per unit weight of fuel. The principal. methods hitherto proposed for accomplishing this have been outlined above and some of their disadvantages stated.

. We havel found that branched-chain paraflin hydrocarbons having 'from about five to about ten carbon atoms per molecule can be easily and economically produced by the reaction of either orl both of the butanes and a substantially saturated heavy hydrocarbon fraction rich in paratlin hydrocarbons having .at least 116 carbon atoms per molecule in the presence of an active aluminum halide. An lideal heavy feed stock is paraffin wax but others which are substantially as eective in causing the butanes t'o react and which are available at relatively low cost are slack wax, l. e. an unsweated parain wax, and

. ,foots oil, which is produced by the sweating op- 25 1 separate operations and the others either do not eration and contains large quantities o1' low melting paraffin waxes. By means of our process premium antiknock motor fuels are produced 'from two materials having low values in themselves in a single economical step.

tions"` necessary to produce iso-octane in this manner. Recently. processes'have been developed in which isobutane is combined iwith a' gaseousoleiin to produce isoparains boiling in the motor fuel range, but in many cases the necessary oleilns are not available for this purpose. x Y

One' of the major problems confronting the petroleum-industry at the present time is the production of sufllcient quantities oiV premium aviation fuels at a reasonable cost and much .3

effort has been directed to themanufacture of Y aviation fuels .consisting largely of branched- `1 chain paraffin hydrocarbons, which yare particu- It is an object'of our invention to provide a process for the production of branched-chain paraln hydrocarbons from the butanes. Another object is to provide a process whereby high antiknook motor fuel constituents can be economically produced from the butanes and heavy materials rich in paramn wax or analogous substances. Other objects, advantages .and uses of our invention will appear from the following detailed description read in conjunction with the drawing which forms a part of this specification and shows in a schematic manner anapparatus suitable for carrying out our invention.

In one of its broad aspects our invention comprises the reaction of'one or both of the butanes and a substantially saturated heavy hydrocarbon (fraction consisting predominantly of paramn hydrocarbons havin'g'at least 16 carbon atoms per molecule in the presence of an active aluminum halide catalyst and in the presence of an activator affording a hydrogen halide under the reaction conditions at a temperature in the range from about F. to about 400 F. and under a pressure sumc'ientto maintain the butanes largelyV in the liquid phase, e. g... about 200 to about 3000 pounds per square inch. Preferably the reaction is carried out'in the presence of freehydrogen under a partial pressure in the range from about300 to about l3000 pounds per square inch, since the hydrogen greatly retards the rate of deactivation of the catalyst.

The butane-containing feed stock of our process can be any 'substantially completely saturated normally gaseous Vfraction rich in at least one of the butanes. Preferably thebutane content is in excess of 50% by volume and includes a considerable proportion, for example, at least 25% of isobutane. Such fractions are available in those refineries carrying out processes in which the olenic content of `a gaseous fraction such as plant `butaneffrom cracking still gas is caused to react, thus leaving the butane relatively free from olens. .Catalytic polymerization and alkylation are examples of such processes. As mentioned above, butane fractions are plentiful in natural gasoline and distillate recovery plants and these are excellent source of gaseous feed lfor our process.

The heavy feed .stock is, as already set forth, a substantially saturated fraction consisting predominantly of paraffin hydrocarbons having at least 16 carbon atoms per molecule. Suitable materials are parain Wax, slack wax, foots oil,

petrolatum, ozocerite, etc. Other very waxy petroleum fractions may also be used, and in general they should` contain at least 50% by weight of parain hydrocarbons having melting points above about 60 F. Another feed stock which can be employed advantageously is the heavy fraction produced as a by-product in the manufacture of iso-octane in the usual way containing the hydrogenated tetramers and heavier 'poly-l mers of lisobutylene.

The butanes and the heavy paramn hydrocarbons should be present in the reaction zonein a. mol `ratio of at least 1:1, and preferably this ratio is in the range from about 2:1 to about 4:1, dependingupon the nature-of the heavy parafl'ins and the degree of conversion desired per pass. Higher yields are obtainable when the heavy paraffins contain relatively large numbers of carbon atoms per moleculeso that it is desirable to use waxy materials having 20 to 30 carbon atoms per molecule if such materials are available. It is also advantageous to use a material practically free from light endsV so that the intermediate boiling product can be separated readily from the unreacted heavy feed stock by fractional distillation. For example, materials having an initial boiling point in the` 'range from 500 F. to 550 F.

are suitable. l

'I'he active Valuminum halide catalyst used in carrying out our invention is preferably an aluminum chloride catalyst, but anhydrous aluminum bromide, for example, is also effective. In acontinuous type of process such as will be described it is preferred-to introduce the catalyst into the reaction zone in the form of a slurry or solution,

for instance in a portion of the feed stock or as a liquid aluminum halidehydrocarbon complex. As will be brought out below, the catalyst complex formed .during the reaction retains its activity for' a considerable'period of time and it is therefore advantageously separated' from the reaction products and recycled.

The concentration of catalyst present in the reaction zone can vary within wide limits, de-

pending primarily upon the temperature, reaction time and catalyst activity or yfreshness. Generally, the catalyst concentration will be within the range from about 5% toabout 30% by weight of the hydrocarbons present, although it will be understood that the actual catalyst consumption will be considerably smaller and generally within Under most conditions we employ an activator with the aluminum 'halide catalyst. When our preferred catalyst, aluminum chloride, is used,

the presence o f an activator is necessary in order that a reasonable reaction rate may be obtained,

but in the case of aluminum bromide the acti- -vator can be dispensed with under some circumstances.

As activator we use a substance affording a hydrogen halide under the reaction conditions, which can be either a hydrogen halide itself, such as hydrogen chloride or hydrogen bromide, or it can be carbon tetrachloride or one of the alkyl halides such as methyl Achloride or bromide, ethyl chloride or bromide, etc. In general the chlorinated andbrominated hydrocarbons, particularly the more volatile ones, are suitable, and even water can be used since hydrogen halide will be generated therefrom by reaction with the catalyst,-but this is not preferred sin'ce the catalyst is thus deactivated more rapidly than would otherwise be the case. Preferably the amount of activator used is sufficient to supply a concentration\in the reaction zone of about 1 to 2 mols' of hydrogen halide per mol of aluminum halide, which will usually be in the range from about 0.1% to 5.0% by weight, based on the reacting hydrocarbons present.

Another important variable which influences the course of the reaction is temperature. In general temperatures ranging from about F. to about 400 F. are suitable, although different reaction times and amounts of catalyst are almost imperative in order that economically practicable results may be obtained at various tem` peratures.` Usually it is preferred to carry out the reaction in .the range from about F. to about'300 F. in order that it may proceed rapidly and Without danger of lover-treatment.

The reaction pressure should besuilcient to keep the butanes largely in the liquid phase and when hydrogen is used the pressure shouldvbe in the range from about 300 to about 3000 pounds per square inch. Preferably, however, the4 hydrogen partial pressure is in the range from about 500 to about 1500 pounds per square inch. The hydrogen employed can be relatively pure or it may contain impurities such as methane as long as the hydrogen content is above about 50 mol per cent.

By carrying out our invention as above described, we are able to convert large amounts of the butanes into branched-chain parafn hydrocarbons suitable for use in aviation fuel. Simultaneously additional amounts of these materials are produced from the heavy feed stock, and all of the desirable hydrocarbon products can be separated from unconverted material by fracdense and form normally liquid branched-chain hydrocarbons. While one might expect that free hydrogen introduced into the reaction zone would impede this process by s aturating the fragments of the heavy feed, this does not occur and the hydrogen acts only on the aluminum halidehydrocarbon complex and helps maintain its activity by preventing the hydrocarbons associated therewith from becoming highly lunsaturated. It is also believed that the mechanism whereby the normal butane is made to enter into the reaction includes the simultaneous isomerization of normal butane Jgto isobutane, which is, of course', relatively more active. Re

gardless of the theory of-the reactions involved,

we have found thatexcellent yields of isoparafflnic hydrocarbons boiling in the motor fuelrange can be obtained according to our invention.

It is apparent that the process of ourinvention can be carried out either batchwise or continuously, although we prefer a continuous operation, and that certain portions of the apparatus must be constructed of corrosion-resistant materials to prevent rapid. deterioration thereof from the active halogen compounds present. Many types of apparatus can be constructed readily by4 one skilled in the art for carrying out our invention,

` 'but we will describe our invention in detail in connection with on1y.one of these as illustrated in the drawing, to which reference is now made.

-The normally gaseous feed as set forth above is introduced into the system by means of pump II) and linesv II, I2 and I3 and thence into a re' Ato insure turbulent flow. Knot-hole mixers o1 other baffle arrangements may be inserted in coil I5 at several places to aid in achieving this result. The heavy feed stock'is passed by means of pump I5 and 'line I1 into a chamber I3 in which it is mixed withactivator supplied by pump I3 in line 20. In thearrangement shown.

3| to separator 32u- The products consist of an aluminum halide-hydrocarbon complex which settles out in the lower portion of separator 32 and an upper layer consisting essentially of unreacted gaseous and heavy feed stocks, branchedchain paraflin hydrocarbons intermediate in boilin'g'range and excess hydrogen. The catalyst complex is continuously withdrawn from sepa- -rator 32 through line 33 and either recycled to line I3 vthrough valve 34, line 35, pump 36 and line 25 or withdrawn from the system through valve 31 and line 38. Under some conditions a portion of the complex may be continuously withdrawn from the system and the remainder recycled, and the substantially. spent complex can of course be regenerated or the aluminum halide recovered therefrom and reintroduced into the system through pump 23. Furthermore, at least a portion of the spent complex can be treated with water or otherwise to furnish hydrogen halide for use as activator in the process.

The remainder of the products from coil I5 are removed from the upper portion of separator 32'through line 33 and valve 40 and introduced into a separator 4I in which a major portion of the .hydrogen is separated due to the reduction in pressure across valve 40. This hydrogen-containing gas which may also contain considerable quantities of hydrogen halide and some normally gaseous parafiins is 'withdrawn from separator 4I through line 42, and can be recycled through valve 43, line 44 and compressor 45 to line 2,8 or all or a portion of it can be vented from the system through valve 46 and line 41.

The lower layer, consisting essentially of hydrocarbons, is removed from separator 4I through line 48 and valve, 43 and introduced into fractionating tower 50. Valve 43 is preferably of which is particularly Vsuitable when the activator is a gas such as hydrogen chloride, only that portion of the activator which dissolves in the heavy A in an, intermediate range, for instance, 200 to 3Go pounds per square inch. The heavy feed now containing dissolved activator enters line I3 by means of pump`2I and line 22, andthe catalyst is likewise Supplied to line I3 by means of pump 23' andvlines24 and 25. When hydrogen is employed this is also introduced into line I3 through compressor, lines 21 and 28 and valve 29, and

it willbe assumed hereinafter that the reaction is carried out in the presence of hydrogen.

The entire reaction mixture from coil I5 lpasses through line 30 and preferably through ay cooler However,

' those vented through line 41. as

sired fractionating pressure.

The` heavy liquids collecting inthe bottom of j fractionator 50 are withdrawn through line 54 and are preferably recycled to line I 3 for further treatment through valve 55, line 55, pump 51 and line 22. Under some conditions it may be desirable to withdraw a portion of these heavy materials from the systeni` and this can be done through valve 53 and line 53.

The overhead passing through line 53 is rich in butanes andV particularly in isobutane and mayl contain such other materials as lare included in the gaseous feeds, and also some hydrogen halide.

This Voverhead is preferably recycled to line I3 through valve 60, line 5I, pump 32 and lines 53 and I2 so that the butanes present may be further converted to normally liquid branched-chain parain hydrocarbons. In order that inert gases may be'prevented from accumulating in the system, a portion of the material in line 53 may be vented from the system eitherr intermittently or continuously through valve 54 and line 55. Free hydrogen and/or hydrogen halide can be recovered from the gases vented through line 55, and well, and these materials returned to the system.

It is apparent that we have described a `novel and useful method of producing branched-chain changers, provisions for fractionating tower control, etc. We do not desire, therefore, to be limited to the specic modifications used in illustrating our invention but only by the scope of the following claims.

We claim:

1. The process of producing a high anti-knock motor fuel rich in branched-chain paraiiin hydrocarbons which comprises contacting a substantially completely saturated normally gaseous fraction containing at least 50 per cent by volume of at least one of the butanes, a substantially saturated heavy hydrocarbon fraction containing at least 50 per cent by weight of paraflin hydrocarbonshaving melting points above' about 60 F., about to 30V per cent of an aluminum chloride catalyst and about. 0.1 to 5.0 per ce'nt of hydrogen chloride based on the weight of hydrocar- Y bons present, and free hydrogen, in a reaction zone maintained at a temperature in the range from about 100 F. to about 400 F. and under a pressure in the range from about 300 to about 3000 pounds per square inch, the butanes in said gaseous fraction and the paranin hydrocarbons in said heavy fraction being present in said reaction zone, in a mol ratio in the range from about 2 to 1 to about 4 to 1, removing the products from said reatcion zone, and separating said high anti-knock motor fuel from said'products.`

2. A process for the production of branchedchain yparain hydrocarbons having between about -ve and about ten carbon atoms'per molecule which comprises the steps of reacting parafns having four carbon atoms per molecule in the presence of a heavy hydrocarbon fraction consisting predominantly of paramn hydrocar- Vbons having at least sixteen carbon atoms per molecule under the catalytic iniluence of an active aluminum halide catalyst, conducting the reaction at a temperature in the range of lbev twee'n about 100 and 400 F.\and under a pressure sufficient to maintain the butanes at least largely a,se9,444

in the liquid phase wherebythere is a net disappearance of parafiins having four carbon atoms per molecule.

3. 'I'he process of claim 2 wherein the mol ratio of C4 parailin and heavy paramn hydrocarbons within the reaction zone is in the range of between about 2:1 and 4:1. v

4. A process for the production of high octane number branched-chain hydrocarbons including those having between about five and about ten carbon atoms per molecule which comprises the steps of subjecting isobutane to the catalytic action of an active aluminum halide in the presence of a substantially saturated heavy hydrocarbon fraction consisting predominantly of paraflin hydrocarbons having at least sixteen carbon atoms per molecule and lunder a pressure suilicient to maintain the isobutane largely in the liquid phase.

5. A process for the production of high octane number branched-chain hydrocarbons including those having between about rive and about ten carbon atoms per molecule which comprises the steps of subjecting to the catalytic action of an active aluminum halide an admixture of butanes consisting of at least 25 volume per cent isobutane and a substantially saturated heavy hydrocarbon fraction consisting predominantly of paraflin hydrocarbons having at least sixteen carbon atoms per molecule, the mol ratios of butanes and heavy paramn hydrocarbons within the reaction zone .being in the range of between about 2:1 and about 4:1.

6. The method of producing large yields of branched-chain paraflinic hydrocarbons of the' gasoline boiling range from lighter and heavier hydrocarbons which method comprises contacting va charging stock consisting essentially of butane and parailin wax with an aluminum chloride catalyst promoted by hydrogen chloride at a temperature within the approximate range of 100 to 400 F. and under a pressure sumcient to main- 25% by volume oLthe butane in the tain liquid phase conversion conditions whereby there is a net disappearance of butanevand'a production of branched-chain hydrocarbons of the gasoline boiling range.

7. The method of claim 6 wherein at least about charging EDMOND L. DOUVILLE. BERNARD L. EVERING.

stock is isobutane. 

